SF-3840 Alert user that available drafting books reflect source text

[RaymondLuong3]

This updates a notice to reflect the change to allow drafting any book available in the source project.

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This change is 

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.04%. Comparing base (dfb04af) to head (d77839e).
✅ All tests successful. No failed tests found.

Additional details and impacted files

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- Coverage   81.04%   81.04%   -0.01%     
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  Files         645      645              
  Lines       41434    41431       -3     
  Branches     6748     6748              
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- Hits        33581    33578       -3     
  Misses       6747     6747              
  Partials     1106     1106              

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[marksvc]

This is reviewable in Devin Review.

[marksvc]

Good code change. But please consider the comment regarding whether we should even have a message.

@marksvc reviewed 4 files and all commit messages, and made 2 comments.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on RaymondLuong3).

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-- commits line 2 at r1:
I observe that we came to this situation from another situation where the user might easily not be able to specify a specific book. And so we are revising the UI from that situation, to the new situation. This patch therefore revises the notice text and behaviour in response to the changed situation.

But suppose we started fresh, with no previous behaviour. The user can select any book in the source. And suppose we consider what text would be important to show on the dialog at this point in the process. Would we write this message? I don't think we would.

The drafting task here is representing the situation of "Please select books from the source, that you want to generate a draft for into the target." With that in mind, it seems unnecessary to then say essentially, "If the source doesn't have a book, then check if it has the book."

I think that in-so-far as we have made it clear that the user is generating a draft from a particular source text, we don't need to also tell the user that they can only generate drafts for books that are in that source text.

If we are concerned that the user might not have recently Synchronized their source text, and therefore a desired book is missing from the list, then we could word messaging about that.
If we are concerned that the user might be confused or mixed up about what source text they are meaning to use for draft generation, then we might instead write text at the top of the dialog, under the title, saying, "Select books to draft from your configured drafting source text, NNRV - Nepali New Revised Version 2012". (Only if that's that's the concern.)